Abstract

A significant part of the electricity cost of commercial buildings in Melbourne is due to high peak demand that usually occurs on hot summer afternoons. Installation of solar PV on commercial facilities to reduce this cost is not as wide spread as it is in the residential section, despite sharp increases in electricity prices and falling solar PV system costs. Existing literature has identified peak demand on transformers servicing commercial buildings in Melbourne as having a high coincidence in timing with high PV system output. This thesis investigates the feasibility of using solar PV to reduce electricity consumption and peak electricity demand in Melbourne commercial buildings to reduce electricity cost. It also investigates the technical issues involved, and whether such a system would be considered financially feasible by businesses in today’s market.

A case study was conducted on a commercial facility (a Coles supermarket) in Melbourne to determine how well its peak demand profile matches PV output from a local array, the reliability of such a system in offsetting peak demand, and the potential savings based on the tariff in place.

The results show that only a maximum of 30% of PV system rated power output can be reliably counted upon to offset peak demand in summer. The timing of high PV output, whilst better than in residential applications, may still not coincide exactly with peak demand periods when using a north facing array to maximise annual energy output. In the case study and for other buildings with early afternoon demand peaks (typical of cooling related demand), an array rotated approximately 50 degrees to the west of True North, would provide an increase in demand offset, and a net increase in financial benefit. This maximum PV penetration could reduce a commercial building’s annual grid electricity cost by $144 per kW installed depending on the tariff structure in place.

PV synched demand management is an alternative that could improve the effectiveness of such a system, by temporarily reducing building demand during periods of low PV output, so that peak demand event is avoided.

In conclusion, commercial buildings with summer peak demand that is substantially higher than winter, are better suited to PV offset due to tariff structures, and solar resource availability. These typically include buildings that have high cooling demands, such as office buildings, supermarkets, universities, and hospitals.